One of the powerful things about director Kathryn Bigelow's searing movie "Detroit" is the amount of time she spends on the toughest scenes to watch.

Instead of using a few flashbacks or a condensed retelling, the movie devotes more than 40 minutes to a dramatization of a horrific police raid and interrogation inside the Algiers Motel annex during Detroit's civil unrest of 1967.

The real-life incident resulted in the killing of three unarmed African-American teenagers. Several other people were badly beaten and terrorized.

According to Bigelow, the virtually real-time approach to depicting what happened 50 years ago was done for important reasons.

"The story hurts," she says, "but it needed to hurt."

Bringing difficult material to the big screen is nothing new for Bigelow, who made history in 2010 by becoming the first woman to win a directing Oscar. After her victory for the Iraq war drama "The Hurt Locker," her next project was the riveting "Zero Dark Thirty," about the search for Osama bin Laden

Now the 65-year-old filmmaker awaits the release of her latest work, which she hopes will encourage conversations about injustices of the past and in contemporary America.

Talking by phone a few days before her appearance at Tuesday's "Detroit" world premiere at Detroit's Fox Theatre, Bigelow says the idea for the movie was brought to her attention in the aftermath of the 2014 shooting death of Michael Brown by a policeman in Ferguson, Mo.

She was learning about the Algiers Motel incident around the same time she found out that the officer who killed Brown wouldn't face charges.

Recalls Bigelow: "I thought, 'OK, that was 50 years ago, and yet it obviously underscores the severity of the situation (now) and how far we have yet to go in order for this country to heal or to come out from under the shadow of this constant inequity.' "

The screenplay for "Detroit" was written by another Oscar winner, Mark Boal, who was Bigelow's collaborator on "The Hurt Locker" and "Zero Dark Thirty."

A journalist-turned-screenwriter, Boal says the idea was one of a dozen or so being considered by his Page 1 production company.

He visited Detroit in summer 2014 and met one of the Algiers Motel survivors, Dramatics singing group cofounder Larry Reed. That, according to Boal, was the turning point for him in deciding to go ahead with the project.

The extensive research done for the movie included the efforts of a team of researchers from Detroit and nearby suburbs, led by Bridge magazine senior editor and former Free Press reporter and editor David Zeman.

Besides Reed, the filmmakers were able to connect with Melvin Dismukes, the private security guard played by John Boyega. ("Star Wars: The Force Awakens") and Julie Delaney, a survivor portrayed by Hannah Murray (HBO's "Game of Thrones").

"The eyewitness accounts were extremely vital to the writer, myself, but as well to the cast," says Bigelow. "They were kind of the cornerstone of understanding this event."

Early on, Bigelow had her own internal debate about the fact that she would be a white woman making a film centering on African-American characters.

She asked herself this: Would she be the perfect person to make this movie? "Absolutely not," she says bluntly. But she knew that it had to get made. "I had to kind of mitigate my own personal reservations with my desire to tell this story. That basically was more important to me, that this story get out there."

Although "Detroit" is an artistic creation, not a documentary, Bigelow wanted it to be as faithful to reality as possible.

Before filming began, she spoke to the actors — an ensemble cast that includes emerging stars as well as big names like Boyega and Anthony Mackie — to make sure they were ready for the attempt to re-create such a terrifying event.

"I think we all shared the fact that this was an important enough story to do and it wouldn't be a comfortable shoot, and yet the content was significant enough that it might be worth the discomfort," she says.

The filming of the motel scenes lasted for several weeks. Bigelow describes how the actors involved bonded through the process and often prayed together before the cameras rolled.

"They went through it as a team. No one was alone. No one felt alone. I think they felt very supported by each other," says Bigelow.

Algee Smith, the actor-singer from BET's "New Edition Story," who grew up in Saginaw, gives a breakthrough performance as Larry, the character based on Reed. At a panel discussion Sunday at the Detroit Historical Museum, Smith described how Bigelow kept filming after scenes were supposed to end in order to capture some improvising.

"She just let us have the floor ... to the point to where you have these certain words on this page, but then she's going to let that scene run for three more minutes. So what are you going to say (in those) three whole minutes? And it better be authentic!" said Smith.

Most of the filming was done in the Boston area. Shooting took place in 2016, a year after the elimination of Michigan's state film incentives.

Most of the filming originally was intended for Detroit, but the lack of incentives and the fact that potential crew members were leaving the Motor City for busy filming hubs like Atlanta brought about a change in plans.

"I would have loved to have shot the whole movie there. We all would have loved to have shot it there had those incentives have been in place," says Bigelow, who made visits here for scouting purposes. In fact, she says, all the locations were selected for a potential Detroit shoot. By the time production switched to Boston, those choices served as a template for finding replacement sites.

"Detroit" did wind up doing several days of filming in October 2016 in Detroit, Hamtramck and Mason, Mich.

The initial reviews for "Detroit" have been quite positive. So was the reaction of many invitation-only guests at the world premiere. Some left wondering how accurate the depiction was and wanting to learn more about the history. A few older viewers walked out in the middle of the screening, saying the violence and racism was too close to what they had lived through in 1967.

Bigelow admits "Detroit" isn't the kind of movie that builds to the satisfying conclusion of justice being done. That wouldn't be accurate to reality. None of the three white Detroit police officers charged in the events related to the deaths was convicted.

So what good can the movie do?

"Well, that's in the hands of the audience who walks out of the theater," says Bigelow, "Hopefully it encourages other stories to see the light of day and there's a dialogue that can begin in order to heal this country, so that we're not looking at this again, getting another alert on our phone about somebody being pulled over for a faulty tail light and being killed for that."

Bigelow hopes "Detroit" can be a part of the process of discussing the wrongs of the past and the systemic racism that still needs to be addressed.

"The catharsis, I think, is yet to come. It is incumbent on us to try to encourage it. To do nothing is not an answer," says Bigelow

Contact Julie Hinds: 313-222-6427 or jhinds@freepress.com.

'Detroit'

Opens in limited release Thursday night at the AMC Star John R in Madison Heights and Bel Air Luxury Cinema in Detroit. Opens in wide release Aug. 4.

Rated R; strong violence, language

2 hours 23 minutes

Read review Thursday at freep.com and in Friday's Movies + Life section